In this paper we will explore the consequences of dark matter interacting with a stepped fluid, where the late-time behavior after the step of dark matter is that of CDM. The layout of the paper is as follows: in Section  we lay out the specific scenarios we wish to consider, namely the WZDR model of [1]} where the dark matter additionally interacts with the scalar. We study the cosmological signals of such a scenario in Section , showing that such scenarios naturally suppress matter power on \(\sim 15 \, \text{Mpc}\times [20\,000/z_{t}]\)  scales and smaller. We perform a global fit in Section  to an extended data set including a wide variety of cosmological datasets, finding a good improvement in fits compared to \(\Lambda \) CDM and WZDR with CDM. Finally, in Section , we conclude.
Supplementary details regarding the WZDR-DM interaction and its implementation in the Boltzmann solver, as well as a full set of posterior densities and best-fit cosmological parameters as determined by our MCMC analysis, are provided in two appendices.
